Electrically controlled stopmotion system



Sept. 30, 1952 HAYES 2,612,127

ELECTRICALLY CONTROLLED STOP-MOTION SYSTEM Filed June 29, 1949 2 SHEETS-SHEET 1 Uwvvn/WL 1 1 0721614 WW a. Mme y Sept. 30, 1952 F. A. HAYES 2,612,127

ELECTRICALLY CONTROLLED STOP-MOTION SYSTEM Filed June 29, 1949 2 SHEETS-SHEET 2 Patented Sept. 30, 1952 ELECTRICALLY CONTROLLED STUP- MOTION SYSTEM Frank A. Hayes, Middletown, N. 1., assignor to The Singer Manufacturing Company, Elizabeth, N. J.,. a corporation of New Jersey Application June 29, 1949, Serial No. 101,943

. 6 Claims. (Cl. 112--219) This invention relates to a control system and more particularly to a motor control system for driving a machine which performs a predetermined work cycle and comes to rest with a positive stop. 7

One of the objects of this invention is to provide a control system for the stop-motion of a group-stitch sewing machine having a directconnected driving motor, which system shall insure that the latch holding the stop-motion lever in the run positionis engaged before the motor can be started.

Another object of this invention is to provide a control system for the stop-motion of a groupstitch sewing machina which system shall provide just suificient rotational energy at. the stop position to impart to the stop motion lever the energy necessary to operate a trimmer knife or any other auxiliary device that may be desirable.

A still further object of this invention is to provide a stop motion control for a machine having a predetermined operating cycle including starting, high speed running, low speed running, and stopping, without the use of mechanical speed-change devices and/or clutches.

With the above and other objects in view, as

will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art. 3

In the drawings, Fig. l is a side elevation of a sewing machine embodying the invention.

Fig. 2 is a top plan view, partially in section taken on the line 2--2 of Fig. 1.

Fig. 3 is a schematic wiring diagram of a motor control system embodying the invention.

Fig. 4 is a detail of elements of the machine Fig. l. r

Fig. 5 is a modification of part of the system of Fig. 3.

Referring to Fig. 1, the machine is constructed with a frame comprising a cylinder bed. or work arm I from which rises the standard 2 carrying a bracket-arm 3 terminating in a hollow head 4. J ournaled within and longitudinally of the arm 3 is the main-shaft 5 from which is derived,

through usual operative connections, thereciproeating movements of the needle-bar G carrying the needle 1. In practice, the needle l cooperates with a suitable loop-taker, not shown, within the free end of the hollow cylinder-bed l.

The work is adapted to be clamped between the upper and lower members of a work-holder 3 which, in the particular embodiment illustrated, is moved to and fro over the work-support to distribute the stitches in accordance with the desired pattern. The present work holder is of the general type disclosed in the patent to Barron, No. 1,205,317, of November 21, 1916, and means for imparting longitudinal and lateral movements to the work-holder 8 is fully described in the patent to Horton, No. 1,051,998, of February 4, 1913.

The stop-motion device comprises .a pivoted stop-motion lever 9 which carries a springpressed plunger-rod I 0 adapted to engage the stopping cam l l fixed to the main shaft 5 in performing the stopping operation. The main shaft 5 carries a driving pulley I2 for belt connection to an electric motor as will be explained presently. The plunger rod I0 is held out of operative relation with said cam by means of a spring-pressed latch lever l3, one end of. which is provided with a hook l4 adapted to engage a notch i5 upon the stop lever 9 to maintain the same in inoperative position in opposition to a spring It. The other end of the latch-lever I3 lies in the path of movement of the tripping lug i1 secured adjustably upon the inner face of a cam wheel l8. This stopmotion device is of the same general type as that shown and described in the aforesaid U. S. patent to Horton, No. 1,051,998 of February 4, 1913, to which reference may be had for a more complete description thereof. It will be understood that, by pulling down on chain 19, an angle lever 26. pivoted at 2!, causes the stop lever 9 to move carrying the plunger-rod it out of engagement with the stopping cam l l, and in this position the machine is ready to operate.

The above description refers to a, conventional group-stitch sewing machine. There will now be described certain electrical control equipment in its relation to certain mechanical elements of the machine. To facilitate an understanding of this structure, reference wil be made to the schematic diagram of Fig. 3 wherein 22 and 23 indicate, respectively, the polyphase and single-phase primary windings of an electrical induction motor of the two-speed type shown and described in the U. S. Patent No. 2,510,468 of Harry B. Fuge, filed September 8, 1948. The rotor of this motor is permanently connected by a belt (not shown) to the pulley I2 to rotate the main-shaft 5 of the sewing machine. A switch S5 is mounted on a plate 24 secured to the machine frame and is operatively connected to a depending portion 25 of the stop lever 9 so that contacts 26 thereof are closed in the run position of the stop lever and are open in the "stop position of said lever.

A switch S2, also mounted on the plate 24, is operatively connected to the outer cam surface 21 of the cam wheel I8. The arrangement is such that when a notched portion 28 of the cam surface is in engagement with the switch follower 29, contacts 30 and 3| are in engagement. At all other times, contact 3I is in engagement with contact 32. A third switch S3 is mounted ona plate 33 secured to the machine frame and ,is operatively connected to the latch lever I3;so that normally, with the stop lever 9 latched in the run" position, contacts 34 are made. When the latch I3 is tripped by the lug I1, contacts '34 open.

A source of polyphase alternating current energy is indicated by LI, L2, L3. .A contactor35 having an operating coil 36, normally open contacts 31, 38, 39 and normally closed contacts 40, controls the flow of current to the motor windings 22 and '23. A-second contactor 4|, having anoperating-coil 42 and normally open contacts Hand 44 is also employed to control the flow of current to the motor windings as will be explained presently.

In order to'simplify the schematic diagram, it has been necessary toshow the stop cam II located on'the opposite side of the stop lever 9 from its actual position as shown in Fig. l but this in no sense alters 'the operation of the system.

Operation The schematic diagram of Fig. '3 represents conditions just afterthe stop motion lever 9 has been thrownto the run position by pulling down on the chain I9. The latch lever I3 holds the stop motion lever '9 in the run position as shown. Contacts '26 of switch SI, contacts 34 of switch S3 and contacts 3|, '32 of switch S2 are closed. A circuit is completed from LI through contacts 34 of switch'S3, contacts 26 of switch SI, contacts 3I, 32 of switch S2, the normally closed contacts 40 of the contactor 35,'thence through the operating coil 42 of the contactor M to L2. This puts voltage onthe'coil 42, and contactor4I operates to close contacts 43 and44 thus connectingthe windings 22 to LI and L3; L2 being permanently connected to said windings. The motor thus comes up to speed and runs as a polyphase induction motor at a speed determined by the number of poles of the winding and the frequency of the supply. This represents the high speed connection, and the cam wheel I 8 is driven in the direction of the arrow and imparts to the workholder 8 the desired motions-as clearly set forth in the aforementioned Horton Patent No.

As the end of the stitching cycle is approached, the follower 29 of the switch S2 drops into the notched portion 28 of the cam surface 21, thus S3, contacts 26 of the switch SI, contacts 3|, 30

of the switch S2, thence through the coil 36 of the contactor 35 to L2. This puts voltage on the coil 36 and the contactor 35 operates to open contacts 40 and to close contacts 31, 38 and 39. Voltage from LI-L2 is thus applied 'to the low-speed winding 23 of the motor which is thus braked to and run at low speed as is clearly set forth in 4 the aforementioned patent application, Serial No. 48,214. Concurrently, a short-circuit is provided around the contacts 34 of the switch S3 by closed contacts 39, and around the contacts 30, 3| of the switch S2 by closed contacts 31. This provides that the switch SI, alone, is available for controlling the operation of the contactor 35 to remove voltage from themotor when the stop motion lever 9 is released to stop position, and insures that the motor torque is available to drive the machine to at least within one shaft revolu- ;tion of -positive;stop position, which would not be the cease if, for example, the operation of the switch S3 were allowed to determine the opera tion of the contactor 35.

lFurthenmovement of the cam wheel I8 causes "the'lugl'l to engage one end of the latch [3, thus .releasing'thezstopqmotion lever 9, which is immediatelyurged into stop position by the spring I6. The contacts 34 of .switch S3 are opened, but this has no electrical efiect because said contacts are-shorted out by the contacts 39 as explained. The follower '2-9 of theswitch S2 rides up out of the notched'portion 28 and opens the contacts 30, 3| and closes the contacts 3I, 32. This, too, has no electrical effect because contacts 30, 3I are shorted out bythe contacts 31 as explained. Finally, the stop motion lever 9 moves into stop position, having been released by the latch lever I3. Switch SI opens, removes voltage from the operating coil 35 and operates the contactor 35 to open contacts 38, thus removing voltage from the low-speed winding 23, by which time the-motor is held stationary by the positive stop of the machine.

It will be observed thatthe circuit is such that the switch S3, operated-by'the latch lever I3 actually controls thestarting of the motor. Thu the hook I4must fully engage the notch 'I 5 before the switch S3 can close its contacts 34to energize the motor windings. This insures that'the stop-motion lever-9 must be fully latched toits run position before the drivingtorque can be applied by the motor. However,'in disconnecting the motor from the supply source at the end of the stitching cycle, it is the switch SI which governs, and not the switch S3. This shift of switch control is effected because-it is desirable to have the motor drive the machine right up to the positive stop position or as near thereto as is practicable so that sufiicient rotational energy will be available to operate trimmers or perform any operation necessary at the end of theistitching cycl Fig. 5 shows a contactor 45 which may be used in substitution for the contactor 35 when it is desired to "eliminate the switch SI from thecircuit. The connectionsare the same as before except that SI has been eliminated and the lead marked To S3 goes directly to S3 instead of going "through the switch SI as before. The operation is the 'same'as explained above except that theswitch S3, operated from the latchlever I3, controls the disconnection of the motor'winding 23 at the end of the stitching cycle. Thus, under these conditions, the motor will be turned off sooner than when the'switch SI governs and less rotational energy is required to be absorbed when the positive stop is reached. This modification finds application "in those cases in which operation of auxiliary devices at the end of the stitching cycle are not necessary.

Having thus set forth the nature of'the invention, what I claim herein is:

1. In a stop-motion system, a machine having an operating shaft, a timing cam connected to said shaft for determining a sequence of operations for said machine, a stop cam carried by said operating shaft, a stop lever spring-biased to engage said stop cam to positively stop said machine in a predetermined shaft position, means for moving said stop lever out of engagement with said stop cam, latch means for holding said stop lever in said out-of-engagement position, means positioned on said timing cam for operating said latch to release said stop lever, an electric motor permanently and drivingly connected to said machine, a source of electrical energy, said motor having selectively a high-speed connection and a low-speed connection with said source of energy, a first contactor for establishing said high-speed connection, a second contactor for establishing said low-speed connection, and control means for said contactors, comprising a first switch operated by said stop lever, a second switch operated by said latch means, and a third switch operated by said timing cam, said switches being operable in sequence to sta t and run the machine at high speed, to transfer to slow speed. and finally to stop the machine positively in a predetermined shaft position.

2. In a sewing machine adapted to perform a definite series of operations, stitch forming mechanism including a reciprocatory needle, a shiftable work-holder, a cam for controlling the shifting movements of said work holder, a stop-motion lever biased to a stop position, a latch lever for holding said stop-motion lever out of said stop position, an electric motor operatively connected to said sewing machine, said motor having two separate primary windings, contactor means for controlling the selective excitation of said windings, and separate switch means operatively responsive to the movements, respectively, of said stop motion lever, said cam, and said latch lever, for controlling the operation of said contactors to select the driving condition for said sewing machine in timed relation with said definite series of operations.

3. In a group-stitch sewing machine. a cam wheel driven by said machine for timing the performance of a definite series of stitching operations, a two-speed motor permanently connected to said sewing machine to drive same, contactors for controlling the starting, the stopping and the speed of said motor, a stop-motion lever, and a latch lever therefor, switch means for controlling said contactors responsively, respectively, to the movement of each of said cam wheel, said stopmotion lever, and said latch lever, said latch lever operated switch being arranged so that the latch must engage the stop-motion lever before the switch can operate.

4. In a sewing machine adapted to perform a definite series of operations, a cam for controlling the cycle of operation of the sewing machine, a two-speed electric motor directly connected to said sewing machine, control means for starting and stopping said motor, and for selecting the speed thereof, said control means including switches operated in timed relation with said cycle of operation, a manually controlled starting lever and a latch for said lever, one of said switches being operated by said latch so that the starting lever must be latched in before said switch operates,

5. An electrically-controlled stop-motion system for a sewing machine, comprising a cam operated by said sewing machine for controlling a cycle of sewing operations, a two speed electric motor having a high-speed winding and a separate low-speed winding and drivingly connected to said sewing machine, a stop-motion lever adapted to be operated to stop said sewing machine in a predetermined shaft position, a latch 'for securing said stop-motion lever in its nonstop position, means for controlling said motor, including switches operated in timed relation to the cycle of sewing operations, one of said switches being operated by said stop-motion lever to disconnect said low-speed motor Winding from a source of power, and another of said switches being operated by said high-speed latch to connect said motor winding to the source of power.

6. In an electrically controlled stop-motion system for a group stitch sewing machine, an operating shaft, a timing cam driven by said shaft for determining a sequence of stitching operations for said sewing machine, a stop cam carried by said operating shaft, a stop lever normally biased for engagement by said stop cam to positively stop said machine in a predetermined shaft position, means for moving said stop lever out of engagement with said stop cam, latch means for holding said stop lever in said out-ofengagement position, means operated by said timing cam for releasing said latch, a two-speed electric motor permanently and drivingly connected to said sewing machine, a source of electrical energy, a first switch operated by said latch means for controlling the connection of said motor to said source of energy for operation at highspeed, a second switch operated by said timing cam for controlling the connection of said motor to said source of energy for braking to and operation at low-speed, and a third switch operated by said stop lever to disconnect said motor from said source of energy to stop said motor.

FRANK A. HAYES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

